1. Area of the Art
The present invention concerns the area of teleconferencing and, more specifically, an improved video teleconferencing device that permits eye contact wherein the remote conferee appears to actually be present in the room.
2. Description of the Background Art
A primary concern in video teleconferencing ergonomics is a lack of eye contact between conferees. Eye contact is not possible with common terminal configurations, because the camera is placed at the perimeter of the display that images a distant conferee, so that the camera does not interfere with a local conferee's viewing of the display. With this configuration the conferees fail to look directly into the camera, which results in the appearance of the conferees looking away and appearing disinterested in the conversation.
Although numerous technologies have been proposed to correct the eye contact problem, many of these technologies suffer from poor image capture quality, poor image display quality, excessive expense, or unacceptably increased terminal bulk. One commonly used component in eye contact systems is a beamsplitter. A beamsplitter is a semireflective transparent panel sometimes called a one way mirror or a semi-silvered mirror. Although even a plain sheet of transparent material such as glass can be employed, it is more common to apply coatings to a transparent substrate to increase its reflectivity.
A common beamsplitter eye contact arrangement consists of a beamsplitter that is mounted in front of a display oriented at about 45 degrees to the display surface. The conferee using the terminal looks through the beamsplitter to view the display. A camera is disposed in front of the beamsplitter and captures an image of the conferee reflected in the semireflective beamsplitter. This technology has a number of drawbacks. First, the 45 degree angle of the beamsplitter placed in front of the display necessarily increases the bulk of the display. Second, if the beamsplitter is illuminated by ambient light, the quality of the image captured by the camera may be seriously degraded. This problem may be avoided by a hood of an opaque material extending from the display to the edge of the beamsplitter so that ambient light does not degrade the reflected image. However, an opaque hood makes the beamsplitter appear even more intrusive with the angled beamsplitter forming a visible barrier in front of the display surface. Whether the display is a computer desktop monitor or a big screen television, the awkwardness of the protruding beamsplitter and camera remains an inefficient use of space.
U.S. Pat. No. 5,117,285 to Smoot attempted to reduce the bulk of this type of terminal by applying polarizers to the display and camera, so that the beamsplitter can be angled more acutely, approximately 30 degrees, without having light from the display interfere with the reflection of the conferee. A drawback to this arrangement is the inherent loss of light caused by the polarizer which further reduces the display image brightness, which has already been reduced by the beamsplitter. Even though this technology reduces the angle of the beamsplitter, it still adds considerable bulk to the terminal and a transparent barrier still remains in front of the display. Also, terminal bulk is further increased by the camera placement, which must protrude far from the display to capture the reflection of the conferee in the 30 degree angled beamsplitter. This becomes a nuisance with desktop conferencing, because the camera is positioned in the conferee's work space where a keyboard is usually placed.
Another eye contact beamsplitter arrangement resolves this protruding camera problem by mounting it behind the beamsplitter. In this arrangement, the display is reflected by the beamsplitter for viewing by the conferee. The light of the reflection conceals the camera behind the beamsplitter. The camera thus captures the image of the conferee through the beamsplitter. If a flat panel display is used or if a CRT display is mounted in a desk's surface and aimed upward, the bulk of this system can be reduced substantially.
However, even with these improvements this arrangement suffers from an additional significant problem: namely the conferee can simultaneously observe the displayed image both in two ways, either by directly viewing the display or by viewing the reflection of the display on the beamsplitter. That is, as the conferee looks at the reflected image, it is easy to glance at an angle and directly view the display below the beamsplitter. The dual visible images in this arrangement are a severe distraction, as the conferee's attention is divided between the light of two images. If the conferee gazes directly at the display (as opposed to the reflection of the display), eye contact will be disrupted because the camera will capture an image of the conferee that appears not to look at the face of the remote conferee.
Prior Art Beamsplitter Arrangements
FIG. 1 illustrates a prior art eye contact beamsplitter arrangement in which the image of a conferee is captured by a camera 4 by means of a reflection in a beamsplitter 6. At the same time the conferee's image is captured, that conferee is able to look through the beamsplitter 6 to view a display 2. A hood 8, usually covered with an opaque material, is typically included to shield the beamsplitter 6 from ambient light. The drawbacks to this arrangement include the increased bulk of the terminal (although a flat panel will minimize this problem), the addition of a transparent barrier in front of the display which affects viewing the display surface, the appearance of the display being recessed far into the terminal creating a tunnel effect and, lastly, the awkward positioning of the camera 4 which intrudes into the conferee's work space.
FIG. 2 is a prior art eye contact beamsplitter arrangement that attempts to reduce the protrusion of the beamsplitter 6 by adding a polarizer 9. Here when properly configured with a second polarizer 11 on the camera 4, the camera 4 can be aimed more directly toward the display 2 without picking up the image on the display 2 through the beamsplitter. Despite some reduction in the angle of the beamsplitter 6, the unit still suffers from excessive bulk, a transparent barrier between the conferee and the viewing surface of the display 2. Also, the camera 4 protrudes awkwardly from the terminal on a stand 12, invading the conferee's work space.
FIG. 3 presents a beamsplitter arrangement in which the conferee views the reflection of the display 2 by the beamsplitter 6. The camera 4 is substantially concealed from view behind the beamsplitter 6 and is aimed through the beamsplitter 6 to directly capture the image of the conferee. As is illustrated, the significant drawback of this arrangement is the fact that the light from the display 2 is visible to the conferee simultaneously at the display 2 and as the reflection of the display 2 in the beamsplitter 6 by the conferee. These two visible images compete for the conferee's attention and add distraction while conferencing, thereby reducing the quality of the conferencing experience.